Self-dispersing waxes as polymer suspension aids

ABSTRACT

Polymer particles of ultrahigh molecular weight poly(alpha-olefins) may be made stable toward agglomeration by suspension within a co-suspension of self-dispersing waxes. This combination prevents polymer agglomeration over time while maintaining good flowability properties. Such materials, ultimately used as pipeline additives to reduce the fluid drag and increase the volumetric throughput, may be shipped and stored for extended periods of time without irreversible loss of the suspension stability.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/406,778 filed Apr. 19, 2006.

TECHNICAL FIELD

The invention relates to processes for producing suspensions ofpolymeric drag reducing agents, and most particularly to processes forproviding suspensions of polymeric drag reducing agents in a form thatis stable during storage, handling and shipping using self-dispersingwaxes

TECHNICAL BACKGROUND

The use of polymers, particularly poly(alpha-olefins) or copolymersthereof, to reduce the drag of a hydrocarbon flowing through a conduit,and hence the energy requirements for such fluid hydrocarbontransportation, is well known. These drag reducing agents or DRAs havetaken various forms in the past, including slurries or dispersions ofground polymers to form free-flowing and pumpable mixtures in liquidmedia. A problem generally experienced with simply grinding thepolyalpha-olefins (PAOs) is that the particles will “cold flow” or sticktogether after the passage of time, thus making it impossible to placethe PAO in the hydrocarbon where drag is to be reduced, in a form ofsuitable surface area, and thus particle size, that will dissolve orotherwise mix with the hydrocarbon in an efficient manner. Further, thegrinding process or mechanical work employed in size reduction tends todegrade the polymer, thereby reducing the drag reduction efficiency ofthe polymer.

In general, the DRA polymer may be obtained via solution polymerizationof an alpha olefin monomer, or a mixture of olefinic monomers, or frombulk polymerization (i.e., without solvent) of such monomer(s). The DRApolymer may then be subsequently made into particulate form by cutting,chopping, granulating, grinding and/or other size reduction, atcryogenic or ambient temperatures. Alternatively, it may be precipitatedfrom solution by addition of a non-solvent component. Mixtures ofpolymer solids from both sources may be used.

Once the polymer DRA is prepared and reduced to appropriate particulateform, it may be incorporated with a liquid carrier to form a slurry. Insome embodiments the liquid carrier is a non-solvent for the polymer DRAand its selection may vary widely. A problem that is often encountered,however, is that there is a natural tendency for such slurries to settleover time, or to separate or agglomerate such that the slurries nolonger maintain a free-flowing and pumpable nature.

Some ways of addressing this problem have been to include (1) apartitioning agent, (2) a wetting agent, and/or (3) a rheology modifierin the slurry together with the carrier liquid and the DRA polymerparticles. These three components, which are frequently all included,may be referred to generally as “suspension aids”. The purpose of thepartitioning agent is to physically hold the polymer DRA particlesurfaces apart. The purpose of the wetting agent is to wet the polymerDRA surface, and the purpose of the rheology modifier is to increase theviscosity of the liquid carrier to slow down polymer DRA particlesettling or rising. In some cases a single ingredient may serve morethan one purpose within the suspension aid package. In one non-limitingembodiment herein a “suspendsion” is defined as a stable slurry.

The liquid carrier is, in some embodiments, a non-solvent for thepolymer DRA and may vary widely. Selections for this component mayinclude both aqueous and non-aqueous liquids, including, for example,water and aqueous solutions of various pH and ionic strength; alcoholsand fatty alcohols; glycols and diols; glycol ethers; glycol esters;mixtures of these; and the like.

The wetting agent is often included in such formulations, particularlyfor aqueous carrier liquids. Without a wetting agent the liquid carrierwould quickly drain away from a non-wetted polymer surface. This wouldresult in a highly separated suspension. Fatty acid waxes have been usedas wetting agents, as well as commercially available surfactants,including, but not necessarily TWEEN™, SPAN™, BRIJ™, and MYRIJ™. Thesesurfactants, which are generally sorbitan esters, ethoxylated sorbitanesters, alcohol ethoxylates and polyoxyethylene fatty acids, areavailable from Uniqema. Other surfactants that have been or may beemployed include, but are not limited to, TERGITOL™ and TRITON™surfactants available from Dow Chemical Company, IGEPAL™ ethoxylatedalkylphenol surfactants available from Rhodia HPCII, and the like.

Inclusion of a partitioning agent may also be generally desirable inthese slurries. This is because polymer DRAs are often in the form ofsoft, tacky particles that will agglomerate, or cold flow, when theirunaltered surfaces come into contact with one another. Commonpartitioning agents employed may include, but are not necessarilylimited to, fatty acid waxes, stearic acid and stearate salts (e.g.alkali earth metal stearates such as calcium stearate and magnesiumstearate), stearamides, polyolefin homopolymers and copolymers ofvarious densities; oxidized polyethylene; polystyrene and copolymers;carbon black and graphites; micronized polyphenylene sulfide (PPS),polyphenylene oxide (PPO), polyamides, polyethylene terephthalate (PET),polybutylene terephthalate (PBT), polyvinyl chloride (PVC); precipitatedand fumed silicas; natural and synthetic clays; organo-clays; aluminumoxides; talc; boric acid; polyanhydride polymers; sterically hinderedalkyl phenol oxidants; magnesium, calcium and barium phosphates,sulfates, carbonates and oxides; mixtures thereof; and the like.

It should be noted, however, that many partitioning agents requireheating to reach maximum effectiveness in a formulation. But heating aprocess stream is often economically disadvantageous in commercialproduction. Often the proportion of partitioning agent levels in a finalDRA formulation may be as high as 10% to react effectiveness. Since thepartitioning agent is a non-active component providing no drag reductionand used only for suspension stability, the more of it that is requiredin the formulation, the higher the cost the product will be without acommensurate increase in performance.

A rheology modifying agent may, in some embodiments, also be added tominimize settling of the polymer DRA slurry. By adding the modifyingagent to the liquid carrier, settling or rising of the DRA polymer maybe hindered or prevented. Common rheology modifying agents include, butare not necessarily limited to, polysaccharides and natural gums,cellulosics, natural or modified starches, synthetic polymers such aspolyvinyl alcohol (PVA), polyethylene oxide (PEO), polyethylene glycol(PEG), polyvinyl pyrrolidone (PVP), and the like. However, thesematerials generally have no particulate properties that would permitthem to serve as a partitioning aid. Rheology modifiers for aqueoussuspensions typically require sufficient hydration in solution so thathydrogen bonding between the polymer chains of the rheology modifiersprovides for weak, temporary inter-chain bonding. This interaction givesrise to a viscosity increase within the aqueous solution. The use ofglycols and other freeze protectants as components in aqueous carrierstypically interfere with the rheology modifier and disable its functionand usefulness.

Another practice to enhance suspension stability is to match thesuspended particle density to the carrier density by using a combinationof carrier components in a proportion such that the overall carriermixture density equals the suspended particle density. A drawback ofthis practice is that there are a limited number of carriers availableat an economical cost that have both the proper densities and thenecessary hydrophobic/hydrophilic properties.

It may be appreciated that considerable resources have been spent onboth chemical and physical techniques for easily and effectivelydelivering drag reducing agents to the fluid that will have its drag orfriction reduced. Yet none of these prior methods has proven entirelysatisfactory. Thus, it would be desirable if a drag reducing agent couldbe developed which is stable during storage, transportation andhandling, that is, does not separate out the DRA particles. In view ofthe above, there is still a need in the art to discover ways to producestabilized polymer DRA slurries that are convenient and economical andwhich do not unacceptably suffer from the drawbacks discussedhereinabove. In non-limiting examples, it would be helpful to develop amethod to produce stable DRA products that avoid the application ofadditional heat and/or avoid grinding of the suspension aid per se.

SUMMARY

There may be provided, in one non-restrictive form, a polymer suspensionthat includes a carrier liquid and a self-dispersing wax, where theself-dispersing wax involves a surfactant property that is provided bythe self-dispersing wax itself or by a separate surfactant. The polymersuspension also includes suspended polymer particles, where optionallythese particles may be DRAs.

In an alternate non-limiting embodiment of the invention, there isprovided a method for forming a polymer suspension involving combiningin any order: a carrier liquid, a self-dispersing wax, and polymerparticles. Upon mixing, the self-dispersing wax spontaneously forms astable suspension of solid wax particles in the carrier liquid in theabsence of applying added heat or grinding to the wax. The polymerparticles are suspended in the stable suspension.

There is also provided in a non-restrictive version a method for forminga polymer suspension that involves introducing a self-dispersing waxinto a carrier liquid, where upon mixing the self-dispersing waxspontaneously forms a stable suspension of solid wax particles in thecarrier liquid. This stable suspension is formed in the absence ofapplying added heat or grinding to the wax. Polymer particles may thenbe introduced into and suspended in the stable suspension to form astable DRA suspension product.

In another non-limiting embodiment of the invention, there is offered ahydrocarbon-containing stream having reduced drag that includes ahydrocarbon and the polymer suspensions described above.

DETAILED DESCRIPTION

It has been discovered that a polymer solution, including a DRA polymersolution, may be hindered and even prevented from separating and/oragglomerating by the use of self-dispersing waxes. The self-dispersingwax, which may be characterized in one non-limiting embodiment as asoft, heat sensitive hydrocarbon or hydrocarbon derivative that issubstantially insoluble in water, may vary widely. By “self-dispersing”herein it is meant that the self-dispersing wax spontaneously forms afinely divided, stable suspension of solid wax particles when added towater, aqueous solutions, and carrier liquids that are a non-solvent forthe polymer. Water or other non-solvent may be understood as a component(or the only component) of the carrier liquid in the final polymer (e.g.DRA) suspension. Further herein, “spontaneous” is defined as “occurringwithout external aid”, such as added heating to or grinding of theself-dispersing wax. It will be appreciated that this definition ofspontaneous does not exclude incidental heating of the wax by thecarrier fluid that may be, but is not limited to be, warmer than thewax, nor does this definition exclude grinding or other size reductionof the polymer (e.g. DRA) itself in a separate step, process orprocedure.

It will be appreciated that the initial form of the wax material may bea solid, paste or a concentrate, and may contain other componentsincluding, but not necessarily limited to, stabilizers and additivesincluding, but not necessarily limited to, surfactants, antioxidants,biocides, encapsulants, and the like. In one non-limiting embodiment,the density of the self-dispersing wax may vary, but may be within ±5%of the density of the carrier liquid, and in another non-restrictiveversion within ±1% thereof. Thus, in this sense the self-dispersingwaxes may be considered to be “density matched” with the carrier fluid.

The self-dispersing wax may be, by itself in water or other carrierliquid, stabilized toward flocculation and agglomeration by asurface-adsorbed layer of surfactant, where the surfactant may bemolecularly the same material as the bulk solid wax, or a distinctlyseparate molecular species from the wax. Most self-dispersing waxes areof the latter form, but some, such as high molecular weight alcoholethoxylates, are at least partially soluble in water such that themajority of the ethoxylate remains as a dispersed solid, while a smallfraction is dispersed in the water and acts as a surfactant.

Stated another way, the self-dispersing wax includes a surfactantproperty where the self-dispersing wax itself has a surfactantcharacteristic or property, and/or the self-dispersing wax contains orincludes a separate surfactant.

The surprising, improved stability of the polymer suspension might beexplained as follows, although it will be appreciated that thecompositions and methods herein are not intended to be limited by anyexplanation, mechanism or theory. The wax dispersion in water or othercarrier liquid is thought to be stabilized by a layer of surfactant,with excess surfactant being dissolved in the water or aqueous phasepresent. When the polymer, such as a DRA polymer, is added, the new,untreated surfaces accept a significant portion of the surfactant fromthe wax surface and the water or aqueous phase. This depletion of thesurface of the wax, on a per surface area basis, may destabilize thestability of the particles such that the wax and the (DRA) polymergenerally associate or loosely agglomerate or reversibly agglomerate orinsecurely aggregate to a degree, providing both partitioning of thepolymer particles (DRA) and surface wetting. The dispersed wax componentis believed to act not only as a partitioning agent to keep tackypolymer particles separated, but as a wetting agent and/or rheologymodifier, in one non-limiting explanation.

It should also be understood that the self-dispersing wax is notadhered, attached, affixed, or permanently connected to the surfaces ofthe suspended polymer particles. In non-limiting instances, while theself-dispersing wax coats the polymer particle surfaces, it is notcovalently bonded thereto, and the self-dispersing wax layer or coatingcould be easily removed if desired, such as by washing. Of course, inthe practice of the method and compositions herein it is desirable forthe wax to contact and coat the polymer particle surfaces, but this isto be understood as different from the wax being adhered, attached,affixed or otherwise part of the polymer particle surfaces.

Advantages of the compositions and methods herein include, but are notnecessarily limited to, the facts that no grinding or addition of heatto the self-dispersing wax is necessary to cause the wax to beeffective. Another potential advantage is that the self-dispersing waxmay be used at a low level, amount or proportion. Yet another possibleadvantage includes the fact that the self-dispersing wax may function asa partitioning aid, a wetting agent, and/or a rheology modifier, or allthree.

In general, the polymer suspensions herein include a carrier liquid, theself-dispersing wax, and suspended polymer particles. As describedabove, the self-dispersing wax may have a density similar to the carrierliquid density, may contain a surfactant, or may itself be a surfactant,and may spontaneously disperse as fine particles. By “fine particles” or“finely divided particles” is meant particles of sufficiently small sizeas to permit the suspension to readily flow, be pumpable and/or bereadily introduced into a flowing hydrocarbon and dissolved thereinwithout extraordinary mixing, agitation or equipment. Some mixing and/oragitation, even at high shear, is expected and acceptable.

The non-solvent (carrier liquid) in some non-restrictive embodiments ofthe invention may include, but is not necessarily limited to,non-hydrocarbon components such as water or aqueous solutions of variouspH and ionic strengths, alcohols and fatty alcohols, glycols and diols,glycol ethers, glycol esters, or mixtures of these. In one non-limitingembodiment, the carrier liquid is water together with one of the othercomponents mentioned. Butyl cellosolve, hexanol, water, and hexyleneglycol are useful in some embodiments of the invention, and hexyleneglycol is particularly helpful in some applications. The bulk ormajority of the carrier fluid may be any of the above materials, oralternatively a blend of like materials, such as a blend of one or morealcohols with one or more glycols and the like. In some non-restrictiveversions, the carrier fluid may also optionally have minor amounts ofdissolved components including, but not necessarily limited to, acids,bases, salts, polymeric thickeners, biocides, etc., which are notuncommon components for DRA slurries.

With respect to the self-dispersing wax, in one non-restrictive versionthe wax may be at least one alcohol ethoxylate having an alcohol moietywith at least 12 carbon atoms and having from 1 to 10 ethoxy moieties orunits. Alternatively, the self-dispersing wax may include at least oneadditional compound that is an alcohol having at least 12 carbon atomsand/or saturated or unsaturated hydrocarbons having at least 12 carbonatoms, and mixtures thereof. In another non-limiting embodiment, wherethe self-dispersing wax has a non-ionic surfactant component, thenon-ionic surfactant component may have a hydrophilic-lipophilic balance(HLB) of less than about 6, and alternatively, a HLB of less than about5.

Other self-dispersing waxes include, but are not necessarily limited to,alkali earth metal stearates (e.g. calcium stearate, magnesiumstearate), a polyolefin separate and different from the suspendedpolymer particles, naturally-occurring waxes, and combinations thereof.Alkali earth metal stearates are known as suspension aids, particularlyin powdered forms, but are not known as self-dispersing waxes per se inthe stable suspensions herein. Specific, but non-limiting examples ofsuitable self-dispersing waxes, which may include known or proprietarysurfactants, include CALSAN® 50 (available from BASF Corporation);SYNPRO® calcium stearate 50BRE (available from Ferro Corporation);AQUACER® 539, CERCOL® 601, AQUACER® 531, AQUACER 532, AQUAMAT® 208 (allavailable from Byk Chemie GmbH); MICHEM® Emulsion 98040M1, MICHEMEmulsion 48040M1, MICHEM Lube 162, MICHEM Emulsion 39235, MICHEM Guard25 (all available from Michelman, Inc.); and UNITHOX® 420, UNITHOX 520and UNITHOX 720 ethoxylates (all available from Baker Petrolite).UNITHOX 420 and UNITHOX 520 are materials that contain 10-30% ofnon-ethoxylated wax, which may be described as ethylene homopolymer or ahigh molecular weight alcohol. In one non-limiting embodiment of theinvention, the self-dispersing waxes suitably employed herein are“micronized”, that is, have dimensions when dispersed in a stablesuspension on the order of a few tens or hundreds of microns. Suitablesizes for the micronized self-dispersing waxes may range between a lowerlimit of about 1 microns and an upper limit of about 200 microns;alternatively, they may have a lower limit of about 5 microns and anupper limit of about of 50 microns.

In one non-limiting embodiment. It is occasionally helpful in somenon-limiting embodiments, but not generally necessary, to add the wax tothe water as a first step in the process. Some wax types, especially thedistinct wax/surfactants such as the MICHEM materials, etc., may beadded to the DRA polymer/water mixture after the two are mixed.

Suitable surfactants to be used with the self-dispersing waxes hereininclude, but are not necessarily limited to, those surfactants mentionedin the Background herein, as well as other alkoxylated, particularlyethoxylated compounds, such as ethoxylated and/or propoxylated alcoholsand/or alkyl phenols; amines and quaternary ammonium salts; alcoholsulfates and phosphates; alcohol ether sulfates and phosphates; betainederivatives; fatty alcohols and fatty acids; stearates and stearamides;oil bean, protein, tallow and vegetable oil derivatives; salts of these;and mixtures of these.

In an alternative, non-limiting embodiment of the compositions andmethods herein, the surfactant property of the self-dispersing wax, orthe inclusion of a surfactant in with the wax may not be as important afeature or characteristic as the fact that the wax is self-dispersing asdescribed herein.

The concentration of self-dispersing wax solids may range from about0.01% to about 30% by weight, based on the entire polymer suspension,and in another non-limiting embodiment may have a lower limit of about0.1 wt % to about 8 wt % as an upper threshold. In another non-limitingembodiment.

The compositions of matter where the polymer particles are a DRA polymerare useful as pipeline additives to reduce the fluid drag and increasethe volumetric transfer (throughput) rate of the transported stream.This additive is typically metered into the flowing liquid within thepipeline over a period of time, e.g., days, weeks, or months, which issimilar to the timeframe for storage and transportation to the point ofuse. Therefore, it is desirable for this material to be fluid to allowfor easy transfer and injection, but not separate and becomemacroscopically inhomogeneous (e.g., settling, floating, or otherwisedestabilize, possibly accompanied by agglomeration to form chunks thatplug filters or will not flow through pipes). Ideally, a homogeneoussuspension of fine particles with low viscosity is desired.

The DRA polymer, used in many types of crude oil and in refined productssuch as gasoline and diesel fuels, is an ultra-high molecular weightpolyalpha-olefin polymer or copolymer. Such materials, formed by variousmethods as granules or particulates during manufacture, tend to “coldflow” together to produce irreversible agglomerates, unless they aresuspended in carrier liquids, herein with the assistance of theself-dispersing waxes.

To be effective upon injection into the pipeline, the drag reducerpolymer particle must dissolve quickly, given that a polymeric dragreducer is effective only when fully dissolved as a large, randompolymer coil in solution. Therefore, the self-dispersing wax must notinhibit dissolution while performing as a suspension aid andpartitioning agent. Additionally, shear degradation must be avoided,which is another reason, in addition to low viscosity, that transferringproducts as slurries is preferred. Transferring polymer solutions, orgels, such as through a high shear pump, will degrade the polymer overtime and lower its effectiveness at drag reduction.

Polyalpha-olefins, which in one non-limiting embodiment are suitableDRAs herein, are polymerized from the monomers or comonomers byconventional techniques and will have molecular weights above 10million. Suitable specific DRA polymers include, but are not limited to,FLO® XL® and FLO® MX drag reducers are available from Baker Petrolite.Solution polymerization followed by precipitation is the process usedfor FLO XL drag reducer production. The intermediate FLO XL cake, formedby filtration of the precipitated polymer, is one source of polymer forthe methods and compositions herein. Bulk polymerization followed bygranulation and grinding is a process for FLO MX production, which mayalso be used in the suspensions and methods herein.

In one non-limiting embodiment of this invention, the granulation and/orgrinding for producing particulate polymer DRA may be conducted atcryogenic or non-cryogenic temperatures. For the purposes of thisinvention, cryogenic temperature is defined as the glass transitiontemperature (T_(g)) of the particular polymer having its size reduced orbeing ground, or below that temperature. It will be appreciated thatT_(g) will vary with the specific polymer being ground. Typically, T_(g)ranges between about −10° C. and about −100° C. (about 14° F. and about−148° F.), in one non-limiting embodiment. As noted, in anothernon-limiting embodiment of the invention, the grinding for producingparticulate polymer drag reducing agent is conducted at ambienttemperature, although the temperature will rise during grinding, ofcourse. Poly(alpha-olefin) is one preferred polymer in one non-limitingembodiment of the invention. In one non-restrictive embodiment of theinvention, the polymer may have its size reduced in one step, or mayhave its size reduced in multiple steps or stages. Such ground orgranulated polymer particles may have a lower limit of about 1 μm and anupper limit of about 60 mm; alternatively, they may have a lower limitof about 50 μm and an upper limit of about of about 12 mm. It ispermissible in an alternate embodiment for the granulated polymer tohave an anti-agglomeration agent thereon, although it is expected thatthe methods and compositions described herein may be successfullypracticed in the absence of any anti-agglomeration agent other than theself-dispersing wax.

Within the context of this invention, the term “granulate” refers to anysize reduction process that produces a product that is relatively largerthan that produced by grinding or homogenizing. Further within thecontext of this invention, “grinding” refers to a size reduction processthat gives a product relatively smaller than that produced by“granulation”. “Grinding” may refer to any milling, pulverization,attrition, or other size reduction that results in particulate polymerdrag reducing agents of the size and type that are the goal of theinvention.

While grinding mills, particularly attrition mills such as Pallmannattrition mills, Munson centrifugal impact mills, Palmer mechanicalreclamation mills, etc. may be used in various non-limiting embodimentsof the invention, other grinding machines may be used in the method ofthis invention as long as the stated goals are achieved.

It should also be understood that although reference is made topoly(alpha-olefins) as a suitable drag reducer for hydrocarbon fluidsthat the invention is not limited to these particular polymers, but thatother polymers known to reduce drag or friction in hydrocarbons, andother polymers in general may be used in the compositions and methods ofthis invention. It must also be understood that “drag reduction”includes, but is not necessarily limited to, any reduction, decrease,retardation, controlling, inhibiting, suppression, or other lowering ofthe effects of friction or drag of a fluid, liquid or hydrocarbonflowing through a pipeline and/or power requirements for transporting ahydrocarbon (or other liquid) through a pipeline. It is not necessaryfor drag or friction to be completely eliminated using the compositionsand methods of this invention, nor for drag or friction to be reduced orlowered by any particular amount for the invention to be consideredsuccessful. Drag reduction is typically manifested as a decrease in thepressure difference across a section of pipeline.

The proportion of polymer in the polymer suspensions may range from alower limit of about 10 wt. % to an upper limit of about 40 wt %;alternatively from a lower limit of about 17 wt. % to an upper limit ofabout 26 wt %, in non-limiting embodiments.

Hydrocarbon systems to which the DRA compositions herein may be appliedinclude, but are not necessarily limited to, any flowing stream that hasa notable hydrocarbon component. By “notable hydrocarbon component” ismeant at least 10 volume percent hydrocarbon or oleaginous material.Hydrocarbon systems include, but are not necessarily limited to,multiphase flow lines (for example oil/water, water/oil, oil/water/gas)in oil and gas production and delivery systems, including gastransmission lines (e.g. gas/condensate, gas/condensate/water). It isexpected that the invention could apply to any hydrocarbon fluid flowingin a pipeline or well, whether or not water or gas is present. It willbe appreciated that by the term “hydrocarbon fluid”, it is expected thatoxygenated hydrocarbons such as alcohols, ethers, and the like areincluded within the definition. Thus, multiphase hydrocarbon-containingsystems (e.g. oil/water, oil/gas, oil/water/gas), such as oil productionflow lines and gas export lines are primary applications for thistechnology. Further, these hydrocarbon systems include, but are notnecessarily limited to, crude oil streams, refined fuel streams, and thelike.

It will also be appreciated that it is difficult, if not impossible, tospecify in advance the amount or proportion of stable DRA polymersuspension that would be suitable and/or effective in any particularhydrocarbon stream since such amount or proportion depends on a widevariety of complex, interrelated factors including, but not necessarilylimited to, the nature of the hydrocarbon stream as defined above, thetemperature of the stream, the expected distance and/or time the DRApolymer is to be effective, the nature of the DRA polymer, thecomposition of the stable DRA polymer suspension, and the like. Suchamounts and proportions are often best determined by empirical efforts,but nevertheless to give some idea of an expected dose or proportion,the amount of stable DRA polymer suspension may range from a lower limitof about 1 ppm to an upper limit of about 250 ppm and in anothernon-limiting embodiment may range from a lower limit of about 10 ppm toan upper limit of about 80 ppm.

The invention will now be further described with respect to specificexamples that are provided only to further illustrate the compositionsand methods herein and not limit them in any way.

EXAMPLE 1

A 7.3 g quantity of UNITHOX 520 (wax density 0.99 g/cc, HLB 4, m.p. 99°C.) was added to 50.1 g of tap water and mixed with a high shear mixerfor 20 minutes. The resulting particle size of the dispersed wax wasabout 20 μm. About 50 g of a precipitated poly(alpha-olefin) polymer DRAmaterial was added, and the combination was mixed for about 1 additionalminute. The resulting polymer DRA suspension showed no signs ofseparation after 1 week and had low viscosity and a fluid character.

EXAMPLE 2

A 13.6 g quantity of MICHEM Lube 162 (wax density 1.0 g/cc, particlesize 0.13 μm, m.p. 85° C.) was added to 34.3 g of tap water andhomogenized. About 50 g of a precipitated poly(alpha-olefin) polymer DRAmaterial was added, and the combination was mixed with a high shearmixer for about 1 minute. The resulting polymer DRA suspension was fluidand showed no signs of separation after 1 week at ambient temperature orwhen centrifuged. No separation was observed when held at 45° C. forseveral days.

EXAMPLE 3

A 300 g quantity of UNITHOX 520 was added to 5880 g of municipal waterand mixed for 30 minutes, giving a 20-30 μm dispersion, and then dilutedwith 1470 g of ethylene glycol. The mixture was charged to arecirculated high-shear rotor-stator grinder, followed by the additionof 2330 g of granules of a bulk poly(alpha-olefin) DRA copolymer. Thiswas ground to about 330 μm average particle size. A 10 g quantity of apolysaccharide was added along with 10 g biocide. The resulting DRAsuspension was thick but fluid and stable against separation. Althoughit is difficult to prove, no size reduction is expected for the waxcomponent during the grinding process. The purpose of the grinding is toreduce the 1 cm³ granules to about 200-400 μm in diameter. The grindingis not intended to reduce the wax particles size.

EXAMPLE 4

A 600 g quantity of CALSAN 50 (50% calcium stearate plus proprietarysurfactant(s), particle size <0.005 on 325 mesh (45 μm)) was added to5880 g of municipal water and mixed for 10 minutes, and then dilutedwith 1470 g of ethylene glycol. The mixture was charged to arecirculated high-shear rotor-stator grinder, followed by the additionof 2330 g of granules of a bulk poly(alpha-olefin) DRA copolymer. Thiswas ground to about 190 μm average particle size.

EXAMPLE 5

A 165 lb quantity of UNITHOX 520 was added to 220 gal of municipal waterand mixed for 30 minutes, giving a 20-30 μm dispersion, and then dilutedwith 452 lb of propylene glycol. The mixture was charged to arecirculated high-shear rotor-stator grinder, followed by the additionof 808 lb of stabilized granules of a bulk poly(alpha-olefin) DRAcopolymer. This was ground to about 253 μm average particle size. Theresulting DRA suspension fluid and stable against separation for severaldays without agitation. The batch was injected into a crude oil pipelineand showed comparable performance to a commercial, alcohol-basedformulation made from the same bulk polymer source.

Many modifications may be made in the compositions and processes of thisinvention without departing from the spirit and scope thereof that aredefined only in the appended claims. For example, the exact nature ofand proportions of polymer particles, carrier liquids, self-dispersingwaxes, and optional additives, etc. may be different from those usedhere. Other alternative or additional processing techniques may be usedor developed to enable the components to be homogeneously blended andwork together well, yet still be within the scope of the invention. Forinstance, an alternative method of introducing the self-dispersing waxmay be used from those exemplified and described herein. Additionally,proportions and types of the various components are expected to beoptimized for each polymer particle type, particularly drag reducingpolymers.

1. A polymer suspension comprising: a carrier liquid; a self-dispersingwax having a non-ionic surfactant component with an HLB of less thanabout 6, where the self-dispersing wax comprises a surfactant propertyprovided from the group consisting of the self-dispersing wax itself,and a separate surfactant; where the suspended polymer particles havesurfaces and the self-dispersing wax is not adhered to the surfaces; andsuspended polymer particles, where the suspended polymer particles arepoly(alpha-olefins) having a molecular weight effective to reduce dragin a flowing hydrocarbon stream.
 2. The polymer suspension of claim 1where the carrier liquid is a non-solvent for the suspended polymerparticles and is selected from the group consisting of water, alcohols,fatty alcohols, glycols, diols, glycol ethers, glycol esters, andmixtures thereof.
 3. The polymer suspension of claim 1 where thedifference between the densities of the self-dispersing wax and thecarrier liquid is within ±5%.
 4. The polymer suspension of claim 1 wherethe self-dispersing wax disperses through the suspension spontaneouslyin the absence of applying added heat or grinding to the wax.
 5. Thepolymer suspension of claim 1 where the self-dispersing wax comprises atleast one alcohol ethoxylate comprising an alcohol moiety having atleast 12 carbon atoms and from 1 to 10 ethoxy moieties.
 6. The polymersuspension of claim 5 where the self-dispersing wax further comprises atleast one additional compound selected from the group consisting ofalcohols having at least 12 carbon atoms, saturated or unsaturatedhydrocarbons having at least 12 carbon atoms and mixtures thereof. 7.The polymer suspension of claim 1 where the self-dispersing wax ispresent in a concentration of from about 0.01 to about 30 wt % of thepolymer suspension.
 8. The polymer suspension of claim 1 where theself-dispersing wax comprises a separate surfactant and the wax isselected from the group consisting of an alkali earth metal stearate, apolyolefin separate from the suspended polymer particles,naturally-occurring waxes, and combinations thereof.
 9. The polymersuspension of claim 1 where the self-dispersing wax is substantiallyinsoluble in water.
 10. A hydrocarbon stream comprising the polymersuspension of claim
 1. 11. A polymer suspension comprising: a carrierliquid; a self-dispersing wax having a non-ionic surfactant componentwith an HLB of less than about 6, where the self-dispersing waxspontaneously forms a stable suspension of solid wax particles in thecarrier liquid, and where the self-dispersing wax comprises a surfactantproperty provided from the group consisting of the self-dispersing waxitself, and a separate surfactant; where the suspended polymer particleshave surfaces and the self-dispersing wax is not adhered to thesurfaces; and suspended polymer particles, where the suspended polymerparticles are poly(alpha-olefins) having a molecular weight effective toreduce drag in a flowing hydrocarbon stream.
 12. The polymer suspensionof claim 11 where the carrier liquid is a non-solvent for the suspendedpolymer particles and is selected from the group consisting of water,alcohols, fatty alcohols, glycols, diols, glycol ethers, glycol esters,and mixtures thereof.
 13. The polymer suspension of claim 11 where thedifference between the densities of the self-dispersing wax and thecarrier liquid is within ±5%.
 14. The polymer suspension of claim 11where the self-dispersing wax comprises at least one alcohol ethoxylatecomprising an alcohol moiety having at least 12 carbon atoms and from 1to 10 ethoxy moieties.
 15. The polymer suspension of claim 11 where theself-dispersing wax is present in a concentration of from about 0.01 toabout 30 wt % of the polymer suspension.
 16. The polymer suspension ofclaim 11 where the self-dispersing wax comprises a separate surfactantand the wax is selected from the group consisting of an alkali earthmetal stearate, a polyolefin separate from the suspended polymerparticles, naturally-occurring waxes, and combinations thereof.
 17. Ahydrocarbon stream comprising the polymer suspension of claim 11.